


Arrhythmia

by despommes



Series: Arrhythmia [1]
Category: Sherlock (TV)
Genre: Kidnapping, M/M, New Orleans, OFC - Freeform, Original Female Character - Freeform, Slash, casefic
Language: English
Status: In-Progress
Published: 2012-04-26
Updated: 2012-06-02
Packaged: 2017-11-04 08:22:31
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,362
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/391759
Author URL: https://archiveofourown.org/users/despommes/pseuds/despommes
Summary: <blockquote class="userstuff">
              <p>"Well done, Mycroft." A malicious sneer envelopes Sherlock's facial features. "I must say, this is one your most upstanding accomplishments to date."</p><p>Mycroft's umbrella stabs into the tile. "Shut the hell up, Sherlock!" he snarls. Sherlock almost jumps at the hostility in his brother's voice. He is struck silent for a rare moment at the anger in Mycroft's eyes. "How dare you? How dare you mock me over this? Is there absolutely no speck of empathy in you, you selfish, ignorant man!"</p><p>Sherlock simply stares back at his brother, whose jaw is clenched and face is flushed.</p><p>Mycroft takes a deep breath, a hand rising to smooth his hair back off his forehead. "I'm aware that the concept is foreign and laugh-worthy to you," he says calmly, fixing Sherlock with a bitter glare. "But family actually means quite a lot to me. Something I had hoped you would have deduced over the years."</p>
            </blockquote>





	1. Palpatations

**Author's Note:**

> I know, everyone's probably going to freak out over the OFC, but don't knock it till you try it.

Lazy Sunday mornings were something of a treasured rarity for John Watson. On the off chance he did get a calm, quiet moment to himself on this sacred day, he would allow himself an hour’s extra sleep, slowly enjoy his tea, and take pleasure in getting a chance to read the whole newspaper before Sherlock can take scissors to it and cut it to bits.

Another reason John’s Sunday morning was passing so peacefully: Sherlock was out. Molly had Sundays off, so Sherlock liked to abuse his privilege of owning a key to Bart’s morgue and collect body parts for his experiments. On that particular morning, with the smell of rain and the threat of a thunderstorm hanging in the atmosphere, he had set out to harvest samples of lung tissue in order to test the damaging effects of motor oil on human alveoli. When Sherlock had kissed him goodbye that morning, John had been half asleep but still able to see the poorly contained glee on the detective’s face at the prospect of more corpse components to carefully destroy.

So John lounges in his favorite armchair, sips contentedly at his earl grey, and leisurely flips through the Sunday news. There’s another picture of Sherlock that day. The photographer only managed to catch his coattails and a hand gloved in black leather covering his face. John smiles to himself and turns the page.

The tranquility of these early hours is broken when the doorbell rings. John slumps in his chair. He groans. It’s barely half-eight, and he’s only one quarter the way through his paper. The tea hasn’t even been given a chance to cool. Mrs. Hudson is out to breakfast with Mrs. Turner from next door, so it’s up to him to answer the door.

The early-morning caller rings the bell one more time. John sighs. “Coming!” he yells out, lifting himself out of the chair. He grumbles all the way down the stairs. It must have been a delivery or salesman; surely a client wouldn’t show up this early on a bloody Sunday.

“Hello,” he mumbles upon opening the door, plastering an annoyed smile on his face.

“Thank god!”

On his doorstep is a teenaged girl. A very small, very thin teenaged girl. The hood of a dark green zip-up sweatshirt obscures most of her face, but John can make out a pair of eyes rimmed in thick, colorful eye-makeup. The strap of a large shoulder bag lies slung over the front of her jacket. The American accent John hears throws him back a bit.

“I thought for sure I was gonna get stuck out here in the rain!” The hood is pulled back, and John’s mouth falls open at the wild mane of rainbow-colored hair that begins to whip about in the pre-storm wind. Honestly, he’s never seen anything like it. The girl’s curls have been dyed into sections of lemon yellow, sea foam green, hot pink, turquoise, and a faded lilac color.

“Um.” He licks his lips. “Okay.”

A hand with a ring on nearly all five fingers is thrust out to him.

“I’m Jemima,” she chirps.

John hesitantly takes her hand, giving a fleeting shake before dropping it. “I—“

“You must be Dr. Watson!” She grins, revealing a set of startlingly white teeth. They’re straight and perfectly shaped, like in a toothpaste commercial. “Is Sherlock Holmes, uh, home?”

Her accent is not only American, but heavily laden with the lazy drawl of the nation’s southernmost states. John’s inner eye suddenly barrages him with images of Spanish moss on plantation houses and sophisticated ladies in white, wide-brimmed hats.

“Not at the moment, no.” He shuffles nervously. “Can I help you?”

“Yes. I’ve got a case for him.” She laughs and her shoulders come up in a bashful shrug. “I e-mailed day before yesterday, but he didn’t reply. Normally I wouldn’t have come without making plans, but it’s very, very urgent, and I desperately help from the both of y’all.”

“Oh.” John looks down the sidewalk. No sign of Sherlock. A distant rumble of thunder goes off. “Well,” he says, glancing at his watch, “I suspect Sherlock will be back soon. You can come in and wait for him, if you like.”

“Yes please.”

John swings the door wider and she eagerly walks inside and out of the threat of being caught in a torrential downpour. She ascends the stairs without being prompted and stops at the doorway to 221B.

“Um, sorry about the mess,” John says, looking around at the perpetual clutter of his flat. A hand comes up to scratch at the back of his skull.

She laughs a little. “That’s okay.”

Before crossing the threshold of stairwell to sitting room, her eyes flicker across the walls and at each corner. John can see them drinking in the elk skull on the wall with its headphones and the spray-painted smiley face outlined in bullet holes. Her brows furrow.

“You can just sit down anywhere. Tea?” he offers, turning for the kitchen.

“Please. Green tea, if you got any.”

So John pours out the pot of cold earl grey and starts the kettle for green tea. He’s actually not fond of green tea at all, but it’s one of Sherlock’s favorites so they keep plenty on hand. While waiting for the water to boil, he peeks around the corner to check on the girl. She is quietly sitting in Sherlock’s chair. Her brown combat boots lie unlaced on the floor, and her legs are crossed underneath her. The green sweatshirt is draped over the chair’s arm, and John sees she’s wearing a white chiffon button-up blouse that’s too big for her. His ears turn a little pink when he realizes that he can practically see through it. The sleeves are rolled up to her elbows. She’s still curiously examining the sitting room, which, he has to agree, is littered with strange objects.

Soon enough, the kettle shrieks, and he pours one mug of pure green tea for his guest and brings it to her. She smiles and takes it from him with a polite “Thanks.”

John sits in the chair and crosses his legs, hands falling into his lap. “So,” he says, “Jemima is it?”

“Yes, sir. Jemima, or Mimi for short.” She blows on her tea. “Is that a real skull?”

John follows her line of sight to the skull perched on the mantle. He’d put a pair of sunglasses on it not too long ago as joke, and they hadn’t been removed as of yet. “Oh, that? Yes. Sherlock’s.”

“The sunglasses his too?”

He chuckles quietly. “Ha, no. Those are mine. Bit of a laugh, you know.”

“Mhmm.” She takes a long gulp of her tea and sets it down on the end table, atop a potholder turned into a makeshift coaster. John opens his mouth to ask her where she’s from, but she beats him to it with a question of her own.

“Is Sherlock Holmes really Mycroft Holmes’s brother?”

To John, that was a bit of an odd question. He thinks on it for a second before nodding. “Yes. He is.”

“Are they close?”

He blinks. “No. No, I wouldn’t say that.”

“Oh.”

“You seem eager to meet him.” John says this with a hint of suspicion. It wouldn’t be the first time some smitten teenage girl has shown up on their doorstep in an attempt to get at the great Sherlock Holmes. If that is the case, he’s prepared to bring this little meeting to an end.

“Just a little curious. I looked him up on the Internet and found your blog. I read some entries. He can really tell everything about somebody from just those tiny little details?”

The front door opens and shuts. John turns his head to the stairwell. Sherlock’s footsteps grow closer and closer until he bursts into the sitting room, pulling a plastic biohazard bag out from underneath his suit jacket. John cringes at the thought of decomposing human flesh that close to Dolce and Gabanna silk.

“Male, fifty-four years of age, sixteen stone, five feet 9 inches. Non-smoker,” he calls to John, striding into the kitchen. “Not the desired specimen, but the best I could come up with. Molly seems to be catching on. Who is in my chair?” The fridge opens and shuts, and John can only hope he put it in the crisper sectioned off for miscellaneous body parts.

“Client,” he replies. 

Sherlock emerges from the kitchen, unbuttoning his suit jacket. Before John can say anything, the girl springs up from her chair and rushes to Sherlock, hand outstretched.

“Hello, Mr. Holmes,” she says, beaming. Sherlock’s hand is clasped in hers before he has time to resist. The metal tinkling of her multiple bracelets as she vigorously shakes his hand rings throughout the room. “I’m so pleased to meet you. I e-mailed a couple days ago, do you remember? I don’t think you replied.”

Sherlock pulls his hand from her grip, a slight curling overtaking his upper lip. The girl’s smile doesn’t falter, not even in the face of Sherlock’s condescending tone when he opens his mouth. “You can hardly expect me to remember an e-mail I might have not even read, much less replied to. Especially without even telling me your name.”

She giggles. “This is gonna sound a little silly, but, well, I read that you could, you know. Learn about people just by looking at them.” Her hands disappear into the pockets of her cut-off denim shorts. “I was kinda hoping you could do that now. With me.”

Sherlock regards her with an almost bored expression on his face. He gives her one long look up-and-down. His hands come up, fingers steepling under his chin as he thinks. Jemima places her hands on her hips and stands up straight, as if she’s putting herself on display. John smiles a little as he observes her. It’s been almost a week since Sherlock’s had a real case, which is partly the reason for the newly relocated lung in their refrigerator, as well as numerous other human tissues now taking up residence in their kitchen.

After nearly a minute, Sherlock’s spine snaps taught. His chin lifts up just an inch higher and he clasps his hand behind his back. “You,” he starts, eyes once again rolling over her small form, “Are seventeen years old.”

She lets out a pleased, surprised sound and claps her hands together once. “Oh, very good! Please, go on. Tell me how.”  
John can feel Sherlock’s ego growing by the millisecond.

“Your plane ticket is sticking out of the outermost pocket of your bag by the chair. It reveals that you flew as an unaccompanied minor, which confirms you are under the age of eighteen. Although you look like you could be anywhere from thirteen years old on, the class ring on your third finger indicates you to be of the graduating class of 2012, this year, so I assumed you’ve skipped ahead in your schooling. Could have been fifteen or sixteen, but seventeen is the safer guess based on your choice in clothing and curvature development in your spine.”

She looks back at John in disbelief for a brief moment. He shrugs, a small proud smile hidden behind his hand. “He’s good.”

“It’s obvious from your accent that you are from the United States; Louisiana to be exact. Your accent is blatantly southern, but not, oh, what’s the word, twangy enough to be from Texas, and not inflected through the nose enough to be from Arkansas, Alabama or anywhere north of there. Too much of a French influence on your vowels to suggest Georgia. Now, as to where in Louisiana, I’d venture a guess and say New Orleans; the underground New Orleans designer Maison de Chic, known only to locals and sold exclusively in New Orleans, sewed your sweatshirt over there.

“You also come from money. Lots of money. The one-carat diamond in your class ring reveals that not only were you born in April, but also that you were born into a substantial fortune. Not to mention the designer that sells the brassier you’re wearing, which, might I add, you don’t need—“

“Sherlock!”

“—Normally sells pieces at about six hundred U.S. dollars. Your phone’s wallpaper picture is of your pet sulcata tortoise, Sammy, who, judging by his size, you’ve had for nearly ten years now. Now, despite the fact that I am incredibly observant and one hundred percent correct about everything I’ve just said, I cannot deduce syllables from your appearance alone. Do you have a name?”

A broad, dazzling grin stretches itself across her face. She crosses her arms and tilts her head. The look in her eyes is fond and impressed at the same time. Sherlock’s brow furrows at her expression, slightly confused.

“My name,” she says, accent clear and sweet as iced tea, “is Jemima Louise Thompson, Mr. Holmes, and I have recently been informed that I am your niece.”

John sees Sherlock’s eyes widen by the smallest fraction of an inch. He has been thrown a curve ball, and his mind is whirring at a million miles a minute to make sense of it. The sounds of gears whizzing nearly fills the air around the flat. John sighs, bringing his hands up to cover his eyes.

So much for his quiet Sunday afternoon.


	2. Tachycardia

**Summary for the Chapter:**

> In which Sherlock is presented with a case.

She has Mycroft’s ears.

Jemima has pushed her wild hair back behind them to search through the large shoulder bag. She’s settled on the sofa, leaving Sherlock’s chair open for him, and is beginning to empty the bag’s contents out on to the coffee table. Sherlock’s hands are laced in his lap and he’s scrutinizing her with his eyes again, doing, John supposes, the exact same thing he is— attempting to line up the similarities between this girl and his brother.

From this far away, John is unable determine her eye color, other than the fact that whatever the pigment, her eyes are very dark. And he can’t even begin to venture a guess as to what shade her hair is naturally. What’s even more startling is her likeness to _Sherlock_. The same skin type—fair and ivory colored, with little patterns of freckles and tiny moles. There is a small smattering on the side of her neck that looks like an upside down, uneven trapezoid. Her hands are finely boned and long-fingered, just like his. She wears some form of sterling silver ring on nearly each finger and her nails are short and trimmed, painted a pearl color. John has no doubt Sherlock has noticed all of this, as well as countless other things he could never hope to pick up on.

They are both snapped out of their separate reveries when she leans over to show them a photograph. She clears her throat. “This is my baby sister, Holly.”

Sherlock takes the picture from her and after a quick glance hands it to John. It’s of a little girl. Her arms are wrapped around the neck of a large chocolate Labrador retriever. Her brown hair has been pulled back into a braid and the large grin she sports is missing two teeth. A hearing aid sits in the shell of her left ear.

Sherlock crosses his legs.

“She does not also claim to be the spawn of my brother, I hope?”

“No; half-sister.” She hands him a yellow folder. “Three days ago she was abducted on a school trip. That’s my personal copy of her case file.”

John’s brow furrows. “I didn’t think the American police force handed out personalized copies of their files.”

“Of course they don’t Dr. Watson,” she replies. “I’m just very resourceful.”

“Yes, right.” John clears his throat. “Resourceful. Suppose we’ll just leave it at that, then.”

“Step-father is a United States Senator,” Sherlock says, mostly to John. He closes the folder and nonchalantly tosses it back on the coffee table. “Presents the possibility of a political rival or angered opposing party member lashing out against him.”

“Daddy’s currently the only Democratic senator in the tri-state area. There are plenty of people that would _love_ to hurt him. He gets threats in the mail on a daily basis from all types: religious groups, ignorant hillbillies, other politicians. The Klan.” She sighs. “A lot from the Klan.”

“All the more assurance that Louisiana’s best will be hunting down your sister and her abductor. Why come all the way to London to ask me?” Sherlock rests his chin on the intertwined fist of both his hands, knuckles brushing his lips. “I may be the only consulting detective in the world, but I mostly specialize in murders or thefts; it is widely known I rarely take on kidnapping cases. Surely you would have gathered that from John’s blog, which you seem to have scoured thoroughly.”

“Louisiana’s best is certainly on my sister’s case. The thing is, Mr. Holmes,” she mutters, the drawl of her accent coloring the syllables like a sunset, “I don’t trust Louisiana’s best to find their ass with both hands. They’ve made absolutely no progress since Holly disappeared, and I don’t expect them to any time soon. The detective heading up the investigation is infuriating at best, unbelievably stupid at worst. Holly has severe hearing loss; she can’t hear anything without her aid, and if that breaks or the battery dies, she won’t have much time—“

“Assuming she isn’t already dead.”

“Jesus, Sherlock!” John hisses, glaring at him.

“—So yes. I flew all the way to London to find my biological father and his brother, the world’s only consulting detective, in hopes that you would help me track down whoever kidnapped my baby sister and help me find her. I know you said you rarely take on kidnapping cases, but _rarely_ is not _never_ and I was really hoping you would make an exception.”

“No.”

Jemima’s mouth had opened to retort, but it promptly snaps shut in disbelief when she hears Sherlock’s answer. Her brows deepen incredulously. “No?” she parrots. “Just no?”

“Yes; just no.” Sherlock uncrosses his legs and stands. “Go home, Miss Thompson,” he says airily, waving a hand in the way of the door. “Your case does not interest me. I have no reason to believe you are actually in any way related to my brother or myself on simply your word alone. Good afternoo—“

“I _ain’t_ leavin’!”

Sherlock’s string of nonchalant dismissals stops at once. Jemima jumps up from the sofa with a small packet of stapled papers clutched in her hand. “You only take on cases that interest you, huh?” She thrusts them out at his chest. “Does Sebastian Moran interest you?” Her fingers twitch. “Well?”

Sherlock’s demeanor changes instantly; his jaw clenches and his spine stiffens defensively. John leans forward tentatively in his chair, bewildered and clueless as to what the name Sebastian Moran meant. “Sherlock?” he asks.

“Get out.”

“What—?”

“Get out, John.” Sherlock’s head swivels sharply in his direction. “Go downstairs and help Mrs. Hudson with her boiler.”

“I don’t know anything about boilers!”

“John! Just go!”

Mumbling, John lifts himself from his armchair and slams the door on his way out. As soon as it’s shut, Sherlock turns on the girl, teeth bared.

“What the hell do you know about Sebastian Moran?”

She sighs and arches an eyebrow at the papers. “Why don’t you take a look, see just what it is that I know?”

Sherlock snatches up the papers and rifles through them, nearly tearing them out of the solitary staple. His eyes narrow and his mouth opens in disbelief. “These are—“

“E-mail correspondence between you and Irene Adler.” Jemima settles herself in John’s armchair. She crosses her bony legs and begins to trace the rim of his abandoned teacup with one pearly fingernail. “Messages sent from March to November, 2011. Between your faked suicide to your gloriously publicized return.”

“Those accounts were _impenetrable_ ,” he spat. “These e-mails were encrypted and permanently deleted from all servers.”

“Yeah, that was all a bit of a problem for maybe, oh, I want to say about twenty minutes.” She pursed her lips. “Gotta say, though, your password was a _tough one_ to crack. Key changes from _Swan Lake_.” She smiled at him. “Clever. Really clever. Would never have guessed it if mama hadn’t forced me to try ballet a hundred years ago.”

“Sebastian Moran was killed in a warehouse fire in Manhattan last October.”

“That’s what you thought, wasn’t it?” She reaches into her seemingly bottomless messenger bag yet again and produced another photograph, this time a candid shot of a darkly tanned man with an almost unnaturally blond buzz cut wearing a pair of sunglasses. The bulky frame and ugly sneer sends Sherlock’s blood boiling and his skin crawling, but the grotesque burn scar crawling up the side of his neck gives him a sickly hot feeling of satisfaction.

“Where was this taken?”

“The French Quarter, in New Orleans. The day my sister was abducted. Don’t think he was the one that took her, though.”

“Of course not.” Sherlock scoffs. “He’s too recognizable, even without the scar. Someone would have noticed.” He bites his thumbnail, mind racing. “Why would he head the abduction of a US Senator’s daughter, though? What could he possibly have to gain?”

“A ransom demand hasn’t been made yet.” Jemima’s head tilts as she observes him. Like she can see what’s going on inside his head.

“He has resources, no need to demand a ransom. No interest in politics, either. Certainly not American politics, at least.” He claps his hands together and brings his fingertips to his lips. “I need data. I need to walk the streets, to see exactly what he is seeing. I’ve got to find him.”

“Find _my sister_.”

“How did you know to look at my e-mail?” He fixed Jemima with a scrutinizing eye. “There was no way you could have possibly known about my connection to Sebastian Moran.”

“I didn’t just look at your e-mail, Mr. Holmes.” She spent a second analyzing her nails before deciding to polish them on the translucent chiffon of her white blouse. “I also went through your financial, medical, and legal records. I hit everything available to me via an internet connection, and a few things not intended to be available to me.”

“I’m assuming you went through Mycroft’s as well.”

“There wasn’t enough time. Your brother—my father—has a far more superior form of lockdown on all his files and records than you do. I dug all that up on you just yesterday in my basement. There wasn’t enough time for me to lurk around through his information without being detected somehow. Give me a few more days and, yeah, I probably could. But I don’t have a few more days.”

“You did all that yesterday?”

“Computers are kind of my _thing_.” She crosses her arms. “I’m one of the top ten cryptographers in the world, third best in the States. Unofficially, of course. I’m too young for the FBI to put on any kind of official list.”

“Yes, the FBI. Your mother’s with the FBI.”

Her eyes widen. “You know who my mother is?”

“Of course I know who your mother is. If you’re claiming to be Mycroft’s, then that narrows down list of possibilities substantially.”

“You remember her. My mother.”

“Yes,” he snorts, allowing a sneer to envelope his lips. “She's not exactly an easy woman to forget.”

Her lip curls distastefully. “Careful how you talk about my mama.”

“Oh, I wouldn’t dream of speaking ill of her. Such a _charming_ woman.”

“So you’ll take the case?” she snaps.

“Well, I’ll have to now, won’t I?” Sherlock taps at the sheets of paper in his hand. “Sebastian Moran, and all that.”

“Wonderful.” She flashes him a bright grin that doesn’t exactly go all the way to her eyes and stands to begin putting her things away. Sherlock notices she doesn’t go to collect her shoes. “So I can expect to see you in New Orleans? You can stay at the house, you and Dr. Watson. We got a ton of guest rooms and all that. I’ll have to tell mama and daddy about all this—“

“They don’t know?”

She grimaces. “Well. I didn’t exactly tell them I was leavin’.”

“You didn’t tell your parents you were flying overseas to drop in on someone you _think_ is a blood relative but have never met before.”

“No, I didn’t, but it’s not exactly the first time I’ve done something like this.” She laughs. “The whole flying outta the country thing, not the, uh, visiting the supposed long-lost family. Which reminds me, do you think you could tell him I’m here? My father, that is.”

“It would be my pleasure,” Sherlock mutters. His mobile was already in his hand, thumb in the midst of pressing the send button on a text message.

_Come to Baker Street at once.  
It seems you have a daughter.  
She’s delightful.  
-SH_

“Thank you kindly.” She pulls a plastic bag out of the pocket of her cut-offs. It’s filled with almonds and an assortment of dried berries. She grasps a few between her fingers and tilts her head back to pop them into her mouth. “B-T-dubs, can I use your shower? Haven’t been able to shower since yesterday morning. Feelin’ kinda gross.”

Sherlock, in the midst of texting John to come back upstairs, lifts his head and gives her a raised eyebrow. “I suppose,” he says slowly.

“Cool.” She grabs her own phone. “I can probably find it on my own. This place doesn’t look too big.” She begins to walk away, stopping briefly to yank off her socks and stuff them into her boots, and grabs a toothbrush out of her bag. “Towels and everything in there right?”

“Yes.”

“’Kay, thanks!”

Sherlock continues to stare at his mobile screen as the little echoes of her bare feet padding on the tile reach his ears. When it flashes with a notification, a small satisfied grin finds his lips.

_For the love of god, Sherlock.  
I’m on my way.  
MH_

He can’t wait for his brother to arrive.

**Author's Note:**

> Please comment and point out any mistakes I might have made!


End file.
